import asyncio


@asyncio.coroutine
def hello():
    print('Hello,world')
    #异步调用asyncio。sleep(1)
    r = yield from asyncio.sleep(1)
    print('Hello again')

#获取EventLoop:
loop = asyncio.get_event_loop()
#执行coroutine
loop.run_until_complete(hello())
loop.close()